Diluent/medication mixing syringe assembly

ABSTRACT

A diluent/medication mixing syringe assembly is described which includes a cannula which extends through a syringe plunger assembly into a reservoir of the syringe assembly. The cannula facilitates injection of a diluent, medication or other fluid into the fluid reservoir of the syringe assembly immediately prior to use for mixing with a medication in the reservoir. In one embodiment, a mixing element is secured to a distal end of the cannula within the reservoir to improve mixing efficiency.

This application claims priority from U.S. Provisional Application Ser. No. 61/101,410 which was filed on Sep. 30, 2008 and is incorporated herein in its entirety by reference.

BACKGROUND

1. Technical Field

The present disclosure relates generally to syringes and, more particularly, to a syringe including a cannula for delivering a diluent or additional medication into the syringe.

2. Background of Related Art

Syringe assemblies which include two chambers for separately storing a diluent and a medication are well known in the art. Typically, multi-chamber syringes which separately store a diluent and a medication are required with medications which are poorly soluble or insoluble in an agueous solution, medications which lack sufficient physical or chemical stability when stored for a prolonged period of time, or medications which include active ingredients which undergo degradation due to interaction with a suspension medium. Such medications are typically stored in a syringe assembly in a dry, lyophilized state separate from a diluent.

Although multi-chamber syringes have proven effective for mixing medications in powder form with a diluent immediately prior to injection into a venous catheter or related device, such syringes typically are complex and, thus, are expensive to manufacture.

Accordingly, a continuing need exists in the medical arts for a syringe assembly which has the capability of mixing a diluent with a medication immediately prior to injection, which is less complex and provides improved mixing capabilities.

SUMMARY

A diluent/medication mixing syringe assembly is disclosed which includes a syringe body having an open proximal end and a fluid outlet on a distal end and a plunger assembly including a plunger body and a plunger head supported on a distal end of the plunger body. The plunger head is slidably and sealingly engaged with an inner wall of the syringe body to define a reservoir in the distal end of the syringe body. A cannula is supported on and extends through the plunger assembly. The cannula defines a longitudinal channel which extends through the plunger assembly into the reservoir. In one embodiment, the plunger rod and the plunger head define a longitudinal bore which is dimensioned to receive the cannula. The cannula can be slidably positioned within the longitudinal bore such that the distal end of the cannula is movable axially within the reservoir. The cannula can also be rotatably positioned within the longitudinal bore.

In one embodiment, a mixing element is supported on the distal end of the cannula within the reservoir. The mixing element can include at least one orifice which extends through the mixing element and is configured to cause turbulence within the reservoir when the cannula is moved axially and/or rotated. The at least one orifice can include a plurality of orifices.

In one embodiment, the proximal end of the cannula includes an adaptor which is configured to releasably engage a supply of fluid. The adaptor can be a female luer type connector.

The syringe assembly can include a sealing member positioned within the longitudinal bore of the plunger rod about the cannula. In one embodiment, the cannula is separable from the syringe assembly and the seal member is configured to seal the longitudinal bore of the plunger assembly when the cannula is separated.

In one embodiment, a male luer connector is positioned on the distal end of the syringe body about the fluid outlet.

A method of mixing a diluent (or additional medication) with a medication in a syringe assembly is also disclosed. The method includes the steps of i) providing a syringe assembly including a syringe body and a plunger assembly wherein the syringe body has an open proximal end and a fluid outlet disposed in the distal end, the plunger assembly includes a plunger body and a plunger head supported on a distal end of the plunger body, the plunger head being slidably and sealingly engaged with an inner wall of the syringe body and defining a reservoir with the syringe body in a distal end of the syringe body, and a cannula extending through the plunger assembly, the cannula defining a longitudinal channel disposed within the reservoir; ii) providing a medication within the reservoir; and iii) introducing a diluent or additional medication into the reservoir via the cannula. In one embodiment, the step of providing a syringe assembly includes providing a mixing element on the distal end of the cannula, wherein the method further includes the step of moving the mixing element within the reservoir to mix the diluent (or additional medication) and the medication. In one embodiment, the medication is in powder form. In one embodiment, the method includes the step of disconnecting the cannula from the syringe assembly after the step of moving the mixing element.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the presently disclosed diluent/medication mixing syringe assembly are disclosed herein with reference to the drawings, wherein:

FIG. 1 is a side perspective view from the distal end of one embodiment of the presently disclosed diluent/medication mixing syringe assembly;

FIG. 2 is a side perspective exploded view from the distal end of the diluent/medication mixing syringe assembly shown in FIG. 1;

FIG. 3 is a side perspective view from the distal end of the diluent/medication mixing syringe assembly shown in FIG. 1 illustrating the distal end of the plunger assembly and mixing disc in phantom;

FIG. 4 is an enlarged perspective view of the distal end of the diluent/medication mixing syringe assembly shown in FIG. 3 illustrating the distal end of the plunger assembly and mixing disc in phantom;

FIG. 5 is a side cross-sectional view of the syringe assembly shown in FIG. 1 during movement of the mixing disc within the reservoir with the plunger assembly in a retracted position;

FIG. 6 is a side cross-sectional view of the syringe assembly shown in FIG. 1 with the plunger assembly in an advanced position; and

FIG. 7 is an enlarged cross-sectional view of the distal end of the plunger assembly.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the presently disclosed diluent/medication mixing syringe assembly and its method of use will now be described in detail with reference to the drawings wherein like reference numerals designate identical or corresponding elements in each of the several views. In this description, the term proximal is generally used to indicate the relative nearness of a referenced item to a user of the device and the term distal is used to indicate the relative remoteness of a referenced item to a user of the device.

FIGS. 1-7 illustrate one embodiment of the presently disclosed diluent/medication mixing syringe assembly shown generally as 10. Briefly, referring to FIGS. 1 and 2, syringe assembly 10 includes a syringe body 12, a plunger assembly 14, a cannula 16 and a mixing element 18 (FIG. 2). Plunger assembly 14 includes a plunger body 20 and a plunger head 22 which is secured to a distal end 20 a of plunger body 20. Plunger head 22 is slidably positioned within syringe body 12 to define a reservoir 24 (FIG. 5) within the distal end of syringe body 12 as will be discussed in further detail below.

Syringe body 12 has an open proximal end 12 a dimensioned to slidably receive plunger body 20 and a distal end 12 b defining a fluid outlet 26. A gripping flange 28 is positioned about proximal end 12 a of syringe body 12. A male luer connector 30 or related structure is formed about fluid outlet 26 on distal end 12 b of syringe body 12. A cap (not shown) is provided to seal fluid outlet 26 prior to use of syringe assembly 10.

Referring also to FIGS. 2-5, plunger body 20 has a proximal end which includes a finger engagement member 32 and a distal end adapted to receive plunger head 22. In one embodiment, the distal end of plunger body 20 includes a stepped portion 34 defining an annular recess 36 dimensioned to receive a proximal annular rib 38 (FIG. 5) formed on plunger head 22. Plunger head 22 is formed of a resilient material, e.g., rubber, which is stretched over stepped portion 34 such that annular rib 38 is received within annular recess 36 to secure plunger head 22 onto the distal end of plunger body 20. Alternatively, plunger head 22 and plunger body 20 may have a variety of different configurations for securing plunger head 22 to plunger body 20. The external surface of plunger head 22 includes one or more ribs 40, e.g., three. Ribs 40 are dimensioned to slidably and sealingly engage an inner wall 42 (FIG. 5) of syringe body 12. Reservoir 24 is defined between a distal face 22 a of plunger head 22 and a distal end 42 a (FIG. 5) of inner wall 42 of syringe body 12.

Referring to FIG. 5, plunger body 20 defines a longitudinal bore 46 which extends the entire length of body 20. Plunger head 22 also defines a bore 48 which is axially aligned with bore 46. Bores 46 and 48 are dimensioned to slidably receive cannula 16 as will be discussed in further detail below.

Cannula 16 is substantially rigid and defines a longitudinal channel 21. Cannula 16 is slidably positioned through bores 46 and 48 of plunger body 20 and plunger head 22, respectively. A distal end 16 a of cannula 16 is movably positioned within reservoir 24 at a position distally of plunger head 22. Mixing element 18 includes a central bore 50 (FIG. 2). Distal end 16 a of cannula 16 is received and secured within central bore 50 of mixing element 18 using any known fastening technique, e.g., adhesives, crimping, welding, etc., such that axial and/or rotational movement of cannula 16 effects corresponding axial and/or rotational movement of mixing element 18. A proximal end 16 b of cannula 16 includes an adaptor 52 which is configured to releasably engage a supply of diluent. Adaptor 52 may include a female luer type connector or like structure. Although not shown, the adaptor 52 may releasably receive a cap (not shown) for sealing proximal end 16 b of cannula 16.

As discussed above, mixing element 18 is secured to the distal end of cannula 16. In one embodiment, mixing element 18 is disc-shaped and includes one or more orifices 56 which extend through mixing element 18. When cannula 16 is moved axially to move mixing element 18 axially within reservoir 24 (FIG. 5), turbulence is created within the mixture located within reservoir 24 to improve the mixing efficiency of the medication and the diluent. In one embodiment, orifices 56 define axes which are angled with respect to a longitudinal axis of cannula 16 such that axial movement of mixing element 18 causes the mixture within reservoir 24 to swirl.

Referring to FIG. 7, a sealing member 60 is supported within longitudinal bore 46 of plunger body 20. As illustrated, bore 46 may include a stepped portion 46 a which receives sealing member 60. In one embodiment, sealing member 60 has a proximal end 60 a which includes an inwardly extending annular rib which slidably and sealingly engages an outer surface of cannula 16. Sealing member 60 can be formed of a resilient material which closes or seals bore 46 of plunger body 20 in the event cannula 16, or a proximal portion thereof, is separated from syringe assembly 10. In that respect, cannula 16 may include a frangible or weakened portion 70 which allows separation of the proximal portion of cannula 16 from the distal portion of cannula 16 upon application of a predetermined axial or torsional force on the proximal end of cannula 16. The predetermined force should be selected to prevent inadvertent separation of the distal and proximal portions of the cannula while facilitating separation by medical personnel. Such predetermined force can be from about two to about five pounds.

Referring to FIGS. 3-6, syringe assembly 10 may be provided with a medication in reservoir 24 which may be in powder form. Alternatively, medication can be drawn into reservoir 24 using known techniques. Prior to use, a cap is provided over fluid outlet 26 and over proximal end 16 b of cannula 16. In use, with a medication positioned within reservoir 24, and a cap (not shown) secured to male luer adaptor 30 over fluid outlet 26, the cap (not shown) over proximal end of cannula 16 is removed. Next, a diluent (or additional medication) is introduced through cannula 16 into reservoir 24. Then, adaptor 30 is resealed and cannula 16 is moved axially and/or rotated to move mixing element 18 within reservoir 24 to effectuate mixing of the medication and the diluent (or additional medication). In one embodiment, as discussed above, the proximal portion of the cannula 16 can be separated from the distal portion of the cannula when adequate mixing has been affected. Thereafter, as shown in FIG. 6, the cap (not shown) over fluid outlet 26 can be removed and plunger assembly 14 can be actuated to dispense the mixture within reservoir 24 through outlet 26.

It will be understood that various modifications may be made to the embodiments disclosed herein. For example, a variety of different seal configurations can be used to seal about the cannula. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto. 

1. A diluent/medication mixing syringe assembly comprising: a syringe body having an open proximal end and a fluid outlet on a distal end; a plunger assembly including a plunger body and a plunger head supported on a distal end of the plunger body, the plunger head slidably and sealingly engaging an inner wall of the syringe body, the plunger head and syringe body defining a reservoir at the distal end of the syringe body; a cannula supported on and extending through the plunger assembly, the cannula defining a longitudinal channel extending through the plunger assembly into the reservoir, the cannula having a proximal end including an adaptor comprising a female luer-type connector configured to releasably engage a supply of fluid; and a sealing member positioned in the longitudinal bore of the plunger body about the cannula formed from a resilient material configured to seal the longitudinal bore upon removal of at least a proximal portion of the cannula from the longitudinal bore, the cannula including a weakened portion facilitating separation of the proximal portion of the cannula from a distal portion of the cannula upon application of a predetermined force on the cannula.
 2. The syringe assembly according to claim 1, wherein the plunger body and the plunger head define a longitudinal bore which is dimensioned to receive the cannula.
 3. The syringe assembly according to claim 2, wherein the cannula is slidably positioned within the longitudinal bore such that the distal end of the cannula is movable axially within the reservoir.
 4. The syringe assembly according to claim 3, wherein the cannula is rotatably positioned within the longitudinal bore.
 5. The syringe assembly according to claim 3, further including a mixing element supported on the distal end of the cannula.
 6. The syringe assembly according to claim 5, wherein the mixing element includes at least one orifice which extends through the mixing element, the at least one orifice being configured to cause turbulence within the reservoir when the cannula is moved axially.
 7. The syringe assembly according to claim 6, wherein the at least one orifice includes a plurality of orifices.
 8. The syringe assembly according to claim 1, wherein the predetermined force is from about two pounds to about five pounds.
 9. The syringe assembly according to claim 8, further including a male luer connector positioned on the distal end of the syringe body about the fluid outlet.
 10. A method of mixing a diluent with a medication in a syringe assembly, the method comprising the following steps: providing a syringe assembly including a syringe body and a plunger assembly, the syringe body having an open proximal end and a fluid outlet disposed in the distal end, the plunger assembly including a plunger body and a plunger head supported on a distal end of the plunger body, the plunger head slidably and sealingly engaging an inner wall of the syringe body and defining a reservoir with the syringe body in a distal end of the syringe body, and a cannula extending through the plunger assembly, the cannula defining a longitudinal channel having a distal end positioned within the reservoir, and a mixing element on the distal end of the cannula; providing a medication within the reservoir; introducing a diluent into the reservoir through the cannula; moving the mixing element within the reservoir to mix the diluent and the medication; and disconnecting the cannula from the syringe assembly after moving the mixing element.
 11. The method according to claim 10, wherein the medication is in powder form. 